Alternative climate products, such as gauge-based gridded data, ground-based weather radar, satellite precipitation and climate reanalysis products, are being increasingly applied for hydrological modelling. This review aims to summarize the studies that have evaluated alternative climate products within Soil and Water Assessment Tool (SWAT) applications and to propose future research directions, primarily for modelers who wish to study limited gauge, ungauged or transnational river basins. A total of 126 articles have been identified since 2004, the majority of which have been published within the last five years. About 58% of the studies were conducted in Asia, mostly in China and India, while another 14% were reported for United States studies. CFSR and TRMM are the most popular applied products in SWAT modelling, followed by PERSIANN, CMADS, APHRODITE, CHIRPS and NEXRAD. Generally, the performance of climate products is region-dependent; e.g., CFSR typically performs well in the United States and South America, but performs more poorly for Asia, Africa and mountainous basin conditions, as compared to other products. In contrast, the CMADS, TRMM, APRHODITE and NEXRAD have shown the strongest capability for supporting SWAT modelling in these regions. However, most of the evaluated products contain only precipitation input; therefore, merging reliable precipitation with CFSR-temperature is recommended for hydro-climatic modelling. Future research directions include: (1) examination of optimal combinations; e.g. CHIRPS-precipitation and CFSR-temperature, for simulating streamflow in different types of river basins; (2) development of a standardized validation scheme which incorporates the commonly accepted products, statistical approaches and temperature variables; (3) further evaluation of existing climate data products to accurately capture extreme events, pattern and indices as well as WGEN statistics; (4) improvement of climate data in terms of averaging approach, bias correction and additional factors or indices integration; and (5) bias correction of CMIP6 climate projections using the optimal climate data combinations.
The Klang River Basin is located in the most densely populated region in Malaysia, with its heavy concentration of industries and population. A systematic study of the pollution to this river system caused by phenolic compounds have been carried out under this project. Analyses of water samples from the Klang River by high performance liquid chromatography (HPLC) with an ultraviolet (UV) detector at 280 nm have shown the presence of some priority phenolic pollutants.
Alkylphenols and most pesticides, especially organochlorine pesticides are endocrine-disrupting chemicals and they usually mimic the female hormone, estrogen. Using these chemicals in our environment would eventually lead us to consume them somehow in the food web. Several rivers in the State of Selangor, Malaysia were selected to monitor the level of alkylphenols and pesticides contamination for several months. The compounds were extracted from the water samples using liquid-liquid extraction method with dichloromethane and ethyl acetate as the extracting solvents. The alkylphenols and pesticides were analyzed by selected ion monitoring (SIM) mode using the quadrapole detector in Shimadzu QP-5000 gas chromatograph-mass spectrometer (GCMS). Recovery of most alkylphenols and pesticides were in the range of 50% to 120%. Trace amounts of the compounds were detected in the river water samples, mainly in the range of parts per trillion. This technique of monitoring the levels of endocrine-disruptors in river water is consistent and cost effective.
Calixarene framework functionalized bio-polymeric magnetic composites (MSp-TDI-calix) were synthesized and utilized as magnetic solid-phase extraction (MSPE) sorbent for the extraction of non-steroidal anti-inflammatory drugs (NSAIDs), namely indoprofen (INP), ketoprofen (KTP), ibuprofen (IBP) and fenoprofen (FNP), from environmental water samples. MSp-TDI-calix was characterized by FT-IR, XRD, FESEM, EDX, VSM and BET analysis, and the results were compared with Sp-TDI and Sp-TDI-calix. To maximize the extraction performance of MSp-TDI-calix decisive MSPE affective parameters such as sorbent amount, extraction time, sample volume, type of organic eluent, volume of organic eluent, desorption time and pH were comprehensively optimized prior to HPLC-DAD determination. The analytical validity of the proposed MSPE method was evaluated under optimized conditions and the following figures of merit were acquired: linearity with good determination coefficient (R2 ≥ 0.991) over the concentration range of 0.5-500 µg/L, limits of detection (LODs) ranged from 0.06-0.26 µg/L and limits of quantitation (LOQ) between 0.20-0.89 µg/L. Excellent reproducibility and repeatability under harsh environment with inter-day and intra-day relative standard deviations were obtained in the range of 2.5-3.2% and 2.4-3.9% respectively. The proposed method was successfully applied for analysis of NSAIDs in tap water, drinking water and river water with recovery efficiency ranging from 88.1-115.8% with %RSD of 1.6-4.6%.
The theory of critical slowing down (CSD) suggests an increasing pattern in the time series of CSD indicators near catastrophic events. This theory has been successfully used as a generic indicator of early warning signals in various fields, including climate research. In this paper, we present an application of CSD on water level data with the aim of producing an early warning signal for floods. To achieve this, we inspect the trend of CSD indicators using quantile estimation instead of using the standard method of Kendall's tau rank correlation, which we found is inconsistent for our data set. For our flood early warning system (FLEWS), quantile estimation is used to provide thresholds to extract the dates associated with significant increases on the time series of the CSD indicators. We apply CSD theory on water level data of Kelantan River and found that it is a reliable technique to produce a FLEWS as it demonstrates an increasing pattern near the flood events. We then apply quantile estimation on the time series of CSD indicators and we manage to establish an early warning signal for ten of the twelve flood events. The other two events are detected on the first day of the flood.
Introduction: Food poisoning usually occurs with the consumption of contaminated food. Some related factors are unsafe water supply, poor sanitation, unhygienic waste disposal and unhygienic practices or poor personal hygiene by food handlers. The purpose of this study is to describe the spatial epidemiology of food poisoning cases in the four districts of Sabah. Methods: This review consists of all food poisoning cases reported from 2011 to 2014 from Kota Kinabalu, Penampang, Putatan and Papar, Sabah. The coordinates used for locations of cases are based on home addresses. Tools such as SPSS v20, ArcGIS v10 and CrimeStat IV were used for data analysis and mapping. Results: A total of 1,787 cases of food poisoning were reported during this review period. In 2011, only Kota Kinabalu and Pa-par illustrated significant food poisoning clusters. Meanwhile, in the year 2012 to 2014, Kota Kinabalu, Penampang and Putatan had clustering of cases. Analysis of nearest neighbour hierarchical clustering analysis showed 32 food poisoning clusters. There were 4 food poisoning points at 500 meters radius around a market place, 2 food poisoning points near a sewage plant and 1 food poisoning point near a water treatment plant. No cases were near a municipal landfill. For rivers and coastline, there were 37 points of food poisoning cases in the proximity of 500 meters. Con-clusion: Food poisoning usually occurs in clusters with possible associated environmental factors.
This article presents a Wall Climbing Robot (WCR) that able to move on ferromagnetic vertical surface to carry out visual inspection process. Visual inspection process is important in the industry to check the condition of storage tank, surface of building, piping or equipment thus can prevents structures collapsing or explosion which would bring a huge loss to the company. Moreover, most of the structures nowadays is expose under the sun and rain, corrosion and cracks could easily occur on the surface after exposing under sunlight and rain a long period of time. Therefore the periodic visual inspection process need to be carry out to detect the damaged occur on the surface of the structure and take action at the fastest time to ensure the safety of the structures and extend the lifespan of the structures. With the well maintenance to the structures, the condition of the structures is monitored and the lifespan is longer. The risk of collapse of the building is decrease by a large margin. Normally, the periodic visual inspection process is performed by operator. Sometime the temporary scaffolding is needed to reach the higher place to carry out the inspection. However, this method create a hazardous environment to the operator and cause the safety of the operator threatened. Therefore, the proposed WCR could help operator to work at the hazardous environment. The permanent magnet is used to provide adhesion for WCR, thus WCR able to move on vertical ferromagnetic surface. The WCR is controlled by operator via wireless remote to reach the higher place or the hazardous environment. The operator then can stream the on the real time images via web browser which connected to the same network with the WCR. Hence, the condition of the surface can be observed.
The current status of silver nanoparticles (AgNPs) in the water environment in Malaysia was examined and reported. For inspection, two rivers and two sewage treatment plants (STPs) were selected. Two activated carbons derived from oil palm (ACfOPS) and coconut (ACfCS) shells were proposed as the adsorbent to remove AgNPs. It was found that the concentrations of AgNPs in the rivers and STPs are in the ranges of 0.13 to 10.16 mg L-1 and 0.13 to 20.02 mg L-1, respectively, with the highest concentration measured in July. ACfOPS and ACfCS removed up to 99.6 and 99.9% of AgNPs, respectively, from the water. The interaction mechanism between AgNPs and the activated carbon surface employed in this work was mainly the electrostatic force interaction via binding Ag+ with O- presented in the activated carbon to form AgO. Fifteen kinetic models were compared statistically to describe the removal of AgNPs. It was found that the experimental adsorption data can be best described using the mixed 1,2-order model. Therefore, this model has the potential to be a candidate for a general model to describe AgNPs adsorption using numerous materials, its validation of which has been confirmed with other material data from previous works.
The Malaysian Department of Environment-Water Quality Index (DOE-WQI) was determined for the Terengganu River basin which is located at the coastal water of the southern South China Sea between July and October 2008. Monthly samplings were carried out at ten sampling stations within the basin. Six parameters listed in DOE-WQI were measured based on standard methods: pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS) and ammonical nitrogen (AN). The results indicated the impact of various anthropogenic activities which contribute to high values of BOD, COD, TSS and AN at middle and downstream stations, as compared with the upstream of the basin. The reverses were true for the pH and DO values. The DOE-WQI ranged from 71.5-94.6% (mean 86.9%), which corresponded to a classification status range from slightly polluted to clean. With respect to the Malaysia National Water Quality Standards (NWQS), the level of most of the parameters measured remained at Class I which is suitable for the sustainable conservation of the natural environment, for water supply without treatment and as well as for very sensitive aquatic species. It is suggested that monitoring should be carried out continuously for proper management of this river basin.
Understanding of the distribution patterns of sediment erosion, concentration and transport in river basins is critically important as sediment plays a major role in river basin hydrophysical and ecological processes. In this study, we proposed an integrated framework for the assessment of sediment dynamics, including soil erosion (SE), suspended sediment load (SSL) and suspended sediment concentration (SSC), and applied this framework to the Mekong River Basin. The Revised Universal Soil Loss Equation (RUSLE) model was adopted with a geographic information system to assess SE and was coupled with a sediment accumulation and a routing scheme to simulate SSL. This framework also analyzed Landsat imagery captured between 1987 and 2000 together with ground observations to interpolate spatio-temporal patterns of SSC. The simulated SSL results from 1987 to 2000 showed the relative root mean square error of 41% and coefficient of determination (R(2)) of 0.89. The polynomial relationship of the near infrared exoatmospheric reflectance and the band 4 wavelength (760-900nm) to the observed SSC at 9 sites demonstrated the good agreement (overall relative RMSE=5.2%, R(2)=0.87). The result found that the severe SE occurs in the upper (China and Lao PDR) and lower (western part of Vietnam) regions. The SSC in the rainy season (June-November) showed increasing and decreasing trends longitudinally in the upper (China and Lao PDR) and lower regions (Cambodia), respectively, while the longitudinal profile of SSL showed a fluctuating trend along the river in the early rainy season. Overall, the results described the unique spatio-temporal patterns of SE, SSL and SSC in the Mekong River Basin. Thus, the proposed integrated framework is useful for elucidating complex process of sediment generation and transport in the land and river systems of large river basins.
Seasonal changes in Ephemeroptera, Plecoptera and Trichoptera (EPT) community was studied at rivers in Gunung Jerai Forest Reserve, Kedah, Malaysia. The rivers were visited monthly from September 2007 to August 2008 to sample aquatic insects using D-pond nets. More EPT were found in the wet season (10664 individuals) compared with the dry season (6599 individuals). In all rivers, ephemeropteran populations was highest during the wet season (z=-2.465, p=0.014). Meanwhile, the plecopteran population was low and almost constant throughout seasons in all rivers (z=-2.280, p=0.023). Trichopterans exhibited the highest peak of abundance in the dry season (z=-6.096, p=0.00). Concomitantly, higher diversity was recorded in the dry season (29 taxa) compared with 25 taxa recorded in wet season from all rivers. Tupah River had the most diverse EPT assemblage during the dry season. In wet season, the abundance of ephemeropterans genera such as Baetis, Platybaetis, Campsoneuria and Thalerosphyrus increased tremendously especially in Teroi River.
The response patterns of microbial functional genes involved in biogeochemical cycles to cadaver decay is a central topic of recent environmental sciences. However, the response mechanisms and pathways of the functional genes associated with the carbon (C) and nitrogen (N) cycling to cadaveric substances such as cadaverine and putrescine remain unclear. This study explored the variation of functional genes associated with C fixation, C degradation and N cycling and their influencing factors under cadaverine, putrescine and mixed treatments. Our results showed only putrescine significantly increased the alpha diversity of C fixation genes, while reducing the alpha diversity of N cycling genes in sediment. For the C cycling, the mixed treatment significantly decreased the total abundance of reductive acetyl-CoA pathway genes (i.e., acsB and acsE) and lig gene linked to lignin degradation in water, while only significantly increasing the hydroxypropionate-hydroxybutylate cycle (i.e., accA) gene abundance in sediment. For the N cycling, mixed treatment significantly decreased the abundance of the nitrification (i.e., amoB), denitrification (i.e., nirS3) genes in water and the assimilation pathway gene (i.e., gdhA) in sediment. Environmental factors (i.e., total carbon and total nitrogen) were all negatively associated with the genes of C and N cycling. Therefore, cadaverine and putrescine exposure may inhibit the pathway in C fixation and N cycling, while promoting C degradation. These findings can offer some new insight for the management of amine pollution caused by animal cadavers.
Dipterocarpaceae is the dominant tree family in the tropical rain forests of Southeast Asia. Borneo is the centre of diversity for the dipterocarps. Identification of hotspots is important for forest and biodiversity conservation efforts. Species Occurrence Models (SOMs) were generated for all 247 species of dipterocarps recorded in Sarawak using herbarium occurrence data and based on the best model selected. The species occurrence density map for each genus and category (endemic and non endemic) was generated by overlaying the SOMs of all species in each genus or category. The species occurrence density maps were analyzed with land cover map from Landsat 7-EMT+ images and protected forest areas for identifying hotspots for conservation in Sarawak. Overlaying the SOM maps revealed that areas in central Sarawak and the southwest region (northwest Borneo around Kuching) are the main hotspots of dipterocarp diversity in Sarawak while the coastal lowland areas in the lower Rejang and Baram River which are mainly peat swamp forest are poorer in species occurrence density. In terms of endemism, as with dipterocarp diversity, the mixed diptercarp forest of central Sarawak is also the most important hotspot. Gap analysis revealed that most protected forest areas are in southwest Sarawak (Bako, Kubah, Tanjung Datu and Gunung Gading National Parks) and in the northern part of Sarawak (Niah, Lambir Hills and Mt Mulu National Parks). This leaves the hotspot in the central part of Sarawak least protected. Protected areas only cover between 2 and 4% of the total areas for the different hotspots (75% species density) while majority of the hotspots that are still forested are outside the protected areas.
Background: The public health issue of consuming groundwater is a major concern because people often extract groundwater directly from the aquifers either through wells or boreholes without treating it with any form of filtration system or chlorine disinfection. Based on the Malaysian National Drinking Water guidelines the current study was designed to provide a better understanding on the variable factors that are influencing the quality of well-water in an urbanised village in Malaysia. Well water quality assessment of heavy metals, chemicals, microbial and physical parameters were carried out for Sungai Buloh Village in the Klang Valley to ensure it was safe for human consumption.
Materials and Methods: Water samples were collected from wells at four sites (Sites A,B,C,D), a river and a tap inside a house in Sungai Buloh village. Soil was sampled from the riverbed and area surrounding the wells. Samples were collected every two months over a one year duration from all sites. The water samples were processed and examined for viruses, coliforms and protozoa as well as for heavy metal contaminants.
Results: The turbidity and colour ranged in the average of 0.57-0.13 Nephelometric Turbidity (NTU) and 4.16-5.00 Total Conjunctive Use (TCU) respectively for all sites except Site C. At Site C the turbidity level was 2.56 ± 1.38 NTU. The well-water was polluted with coliforms (1.2 to 2.4 x 103 CFU/100 ml) in all sites, E. coli (0.12 - 4 x 102 CFU/100 ml CFU/ 100 ml) and Cryptosporidium oocysts (0.4 cysts/100 ml). All the heavy metals and chemical parameters were within the Malaysian Guidelines’ limits except manganese. The average pH ranged from 5.44 - 6.62 and the temperature was 28 ºC.
Conclusion: In summary, the well water at Sungai Buloh is considered unsafe for consumption due to pollution. Therefore the major thrust will be to provide better quality of drinking water to the residents of the village.
The development of GPS tags for tracking wildlife has revolutionised the study of home ranges, habitat use and behaviour. Concomitantly, there have been rapid developments in methods for estimating habitat use from GPS data. In combination, these changes can cause challenges in choosing the best methods for estimating home ranges. In primatology, this issue has received little attention, as there have been few GPS collar-based studies to date. However, as advancing technology is making collaring studies more feasible, there is a need for the analysis to advance alongside the technology. Here, using a high quality GPS collaring data set from 10 proboscis monkeys (Nasalis larvatus), we aimed to: 1) compare home range estimates from the most commonly used method in primatology, the grid-cell method, with three recent methods designed for large and/or temporally correlated GPS data sets; 2) evaluate how well these methods identify known physical barriers (e.g. rivers); and 3) test the robustness of the different methods to data containing either less frequent or random losses of GPS fixes. Biased random bridges had the best overall performance, combining a high level of agreement between the raw data and estimated utilisation distribution with a relatively low sensitivity to reduced fixed frequency or loss of data. It estimated the home range of proboscis monkeys to be 24-165 ha (mean 80.89 ha). The grid-cell method and approaches based on local convex hulls had some advantages including simplicity and excellent barrier identification, respectively, but lower overall performance. With the most suitable model, or combination of models, it is possible to understand more fully the patterns, causes, and potential consequences that disturbances could have on an animal, and accordingly be used to assist in the management and restoration of degraded landscapes.
This is the first study on the seasonal biodiversity of black flies and evaluation of ecological factors influencing their distribution at Doi Pha Hom Pok National Park, northern Thailand. Larvae were collected from six fixed-stream sites in relation to altitude gradients from May 2011 to April 2013. The water temperature, water pH, conductivity, total dissolved solids (TDS), salt, water velocity, stream width and depth, streambed particle sizes, riparian vegetation, and canopy cover were recorded from each site. Monthly collections from the six sites yielded 5475 last-instar larvae, belonging to 29 black fly species. The most frequently found species from all sites were Simulium asakoae (100%) followed by Simulium yuphae (83.3%), and Simulium chiangdaoense, Simulium gombakense, Simulium phahompokense, Simulium fruticosum, Simulium maeaiense and Simulium fenestratum (66.6%). Of the 5475 last-instar larvae, S. maeaiense (19.3%), S. chiangdaoense (15.8%) and S. asakoae (14.8%), were the three most abundant species. The Shannon diversity index (H) at the six sites with different altitudes of 2100m, 2000m, 1500m, 1400m, 700m, and 500m above mean sea level, were 2.042, 1.832, 2.158, 2.123, 1.821 and 1.822, respectively. The Shannon index and number of taxa in the cold season were higher than those in the rainy and hot seasons. Principal component analysis (PCA) indicated that at least three principal components have eigen values >1.0 and accounted for 93.5% of the total variability of ecological factors among sampling sites. The Canonical correspondence analyses (CCA) showed that most species had a trend towards altitude, canopy cover, riparian vegetation and water velocity.
High population density and economic development attributing to the changes in water quality in Pa Sak River, Lopburi River, and Mekong River have attracted great attention. This research aimed to determine the pollution of heavy metals in collected clams at three different study sites. Bioaccumulation of heavy metals in Asian clam (Corbicula fluminea) may be likely to cause serious health effects on human beings. The clams sampled from three different rivers (Mekong, Pa Sak, and Lopburi) from Thailand were analyzed for the presence of heavy metals (Zn, Cu, Cd, Cr, Mn, and Pb) with an air-acetylene flame atomic absorption spectrophotometer (AAS). Among the heavy metals studied, Zn was recorded as having the highest concentration (127.33-163.65 μg/g) among the three rivers. The observed mean concentration of Cu was in the range of 84.61-127.15 μg/g followed by Mn (13.96-100.63 μg/g), Cr (5.79-15.00 μg/g), Pb (3.43-8.55 μg/g), and Cd (0.88-1.95 μg/g). Overall, Asian clam from Pa Sak River was found to contain high concentrations of Zn, Cu, Cd, Cr, and Pb compared to Mekong and Lopburi River.
Knowledge of the fundamental aspects of ecology such as the patterns of fish species distribution and biodiversity in the forest streams is the first and basic step to develop effective conservation strategies. Yet, studies on altitudinal changes of fish composition and assemblages in Bornean forest streams are scarce despite being one of the hotspots of biodiversity conservation. Hence, surveys on freshwater fish composition along the altitudinal gradients of the Baleh River Basin in Sarawak, Borneo were conducted from April 2014 to August 2015. The Baleh River Basin was divided into seven altitudinal groups with a total of 72 stations. Group elevation ranged from 53 to 269 m above sea level. The fish samples and environmental parameters were taken concurrently during samplings. A total of 3565 specimens belonging to six orders, 14 families, and 76 species were found in the present study. The most dominant family in the Baleh River Basin was Cyprinidae (74.4%), followed by Gastromyzontidae (16.2%) while the most dominant species was Tor tambra (12.9%), followed by Lobocheilos ovalis (12.3%). Fish abundance significantly higher at high altitude sites than those at low altitude sites except for Mengiong River which has the lowest fish abundance despite with high elevation. Species richness was found significantly lower in midstream segment. Noticeable altitudinal gradient of fish assemblages was observed along the Baleh River except a discontinuity at the midstream segment which is attributable to the poorer quality inflow from the Mengiong River coupled with the meandering feature of the segment. Fish abundance was significantly and positively correlated with elevation, water pH and conductivity while negatively correlated with turbidity. Anthropogenic activities in the Baleh River Basin had altered the environmental variables thus disrupted the altitudinal gradient of fish assemblages. This phenomenon is apparent when the Canonical Correspondence Analysis (CCA) revealed that the first axis (CCA1) explained 42.5% of the variation and has positive loading on dissolved oxygen (DO) and negative loading on water conductivity; whereas CCA2 explained 37.5% of the variation and positively loaded on elevation, water pH, and DO. The results demonstrated that Gastromyzon fasciatus preferred more oxygenated water than Protomyzon sp., G. sp 1, and G. punctulatus although they are all from Gastromyzontidae family that inhabiting high altitude sites. Barbonymus schwanenfeldii was also found most abundant with elevated dissolved oxygen value. On the other hand, Rasbora volzii and R. hosii inhabiting lower altitude sites with less oxygenated and more acidic water.
A depth-averaged numerical model was developed to study tidal circulation and suspended sediment transport in the gulf of Khambhat along the west coast of India. The spatial resolution of the model is 750m x 750m. A 2-D fine resolution (150 m x 150 m) model for the lower part of the Narmada estuary is coupled with the coarser gulf model to simulate the flow features in the lower estuary. The model dynamics and basic formulation remain the same for both the gulf model and the estuary model. The models are barotropic, based on the shallow water equations and neglect horizontal diffusion and wind stress terms in the momentum equations. The models are fully non-linear and use a semi-explicit finite difference scheme to solve mass, momentum, and advection- diffusion equation for suspended sediments in a horizontal plane. The erosion and deposition have been computed by an empirically developed source and sink term in the suspended sediment equation. The tide in the gulf is mainly represented in the model by the semi-diurnal M2 constituent. Meanwhile, fresh water discharge from the rivers joining the gulf had also been considered. Numerical experiments were carried out to study the circulation and suspended sediment concentrations in the gulf and estuarine region.